Acoustic Emission (AE) sensors have been used for failure analysis in metal structures because deformations due to structural impacts or shifting produce acoustical waves that travel through the structure. For the same reason, the automotive industry has considered using AE sensors to detect acoustic wave energy in the frame of a vehicle for purposes of recognizing a crash event for which supplemental restraints such as air bags should be deployed. See, for example, the U.S. Pat. No. 4,346,914 to Livers et al. and the U.S. Pat. No. 4,842,301 to Feldmaier. In Feldmaier, for instance, AE sensors attached to the vehicle frame rails near the front of the vehicle produce acoustic wave energy signals, and a filter circuit isolates the signal content associated with deformation in order to discriminate crash events from abuse events; supplemental restraints are deployed when the amplitude and duration of the isolated signal satisfy predetermined criteria.